Nexus S with Android 2.3.6

I can use my VoIP account without problems on my laptop with a client. This tells me that the Router, WiFi and everything beyond the router in the big black box we call "internet" works fine.

Now installed the same account on my phone. Cannot make phone calls, the only thing that happens is that a millisecond after I press "dial" the call has ended but it also shows a call duration, either 11:13 or 4:15 minutes. On the website of my account no dial attempts are logged, so my dialling attempt doesn't get that far. I actually suspect it goes at max to the router, but not one inch further.

Any idea how to fix that?

update: Installed SIP Droid, this works but it ignores the caller ID even though I have installed this on both, the SIP Droid client and the VoIP provider website.

Try "csipsimple". It's the best SIP tool I've found for Android. Basically gives you a much better interface to the internal SIP client in Android. Supports multiple accounts, and integrated into the dialer.